Determination of doubly charged europium, ytterbium and samarium ions generated by anodic polarization of their amalgams in aqueous solutions

A method of direct measurement of redox potentials of Sm3+-Sm2+, Yb3+-Yb2+, Eu3+-Eu2+ pairs is described during anodic oxidation of these metal amalgams. The process has been carried out both at constant current intensity and at constant potential. The platinum plate has been used as cathode, SCE has been taken as a reference electrode, and chloride-acetate buffer as a background. Sodium sulphate has been added to the background to stabilize Ln2+ ions, chlorides of corresponding metals - to produce Ln3+-Ln2+ pair. It is found out that in the Sm2+, Yb2+, Eu2+ series the reducing ability of Ln2+ decreases, that's why the time of Eu2+ existence in solution is longer in comparison with Yb2+ and Sm2+ ions